Performing a performance analysis on my site.

Intending to check:

  • PageSpeed Insights (lighthouse, lab) data
  • Real World Chrome User Experience Report (CrUX), Web Core Vitals (field) data

Reason: CrUX data does seems inaccurate, and is presenting statistics that are worst than actual user experience

Steps Taken

  1. Access the PageSpeed Insights Console
  2. Enter my URL and hit Analyze
  3. PageSpeed Insights (Lighthouse, Lab) data is displayed -- However, CrUX (real user data) is not displayed

PageSpeed Insights vs Dev Tools (Discrepant)

The PageInsights Lighthouse Report results is discrepant with the results found via Dev Tools.
This makes it tricky for us to assess whether we should optimise the page performance further (because performance is an SEO ranking factor)

PageSpeed Insights (Lighthouse) Report

For example, see the screenshot from PageSpeed Insights for the largest Contentful pain downloaded -- a total of 1300ms to fully render the image: enter image description here

Chrome Dev Tools Report

The actual time required to download and render the same image is less than 400ms when we checked Dev Tools (we used incognito so that browser cache etc. is removed). Note that this is significantly different from the 1300ms reported in PageSpeed Insights. See screenshot below for reference:

  1. The document itself took approximately 224.43ms: enter image description here
  2. Afterwhich, the image was queued at 224.88ms, and finished downloading in 64.72 ms enter image description here

Using the above dev tools, the largest Contentful download took less than 400ms (compared to 1300ms reported in PageSpeed Insights)

Issue - Unable to Access Real User Data/Report

Chrome User Experience Report (CrUX)

The CrUX data is not displayed. The reason provided was that there is insufficient real-world data. Please see the screenshot below:

enter image description here

Google Search Console

However, checking Google Search Console - we can see steady traffic accessing the website (the number is increasing too). See the screenshot from our Google Search Console:

enter image description here

Core Web Vitals (GSC)

However, do note that Core Web Vitals within the GSC is also indicating that there is insufficient usage. Please see screenshot below:

enter image description here


We wanted to understand from the community:

  1. Are there any other alternatives to measure page speed accurately?
  2. Would you assume that the dev tools are providing results (that Google will use to rank SEO)
  3. Any advise regarding why Web Core Vitals, and CrUX is not showing despite steady traffic to the site?

Thank You

Thanks in advance. Let us know if there is any further information that we can furnish!

1 Answer 1

  1. Yes, you can start gathering and tracking your own real user data. We gather the data with GA4, send it to BigQuery where we process it, then report on it using Looker Studio. Google has provided a web-vitals script to help you do that. There are articles out there to help you set it up (I've written one). There are also some third-party solutions that can make it easier.

  2. Google only uses real user data from CrUX, which has a very small SEO effect. The dev tools data is just for your use.

  3. You will need a lot more traffic than a few visits a day to reach the threshold where they will report the data.

  • Noted with thanks. Will checkout the script! And reach out if there are further issues! You also mentioned it has a very small SEO effect. For a small scale operation, would it be an okay judgement -- to just base performance based on dev tools (assuming that I always disable browser cache) Commented May 25 at 10:40

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.